Friend beginning to move tree (4)
I believe the answer is:
palm
'tree' is the definition.
(palm tree is a kind of tree)
'friend beginning to move' is the wordplay.
'friend' becomes 'pal' (pal can mean a friend).
'beginning to' indicates taking the first letters.
The initial letter of 'move' is 'm'.
'pal'+'m'='PALM'
(Other definitions for palm that I've seen before include "Tree symbolising victory" , "Obscure" , "Tropical tree; conceal" , "Coconut-bearing tree" , "Queen; station" .)